There are known portable liquid container designs which are adapted for military applications under field conditions. Well-known examples are the canteen and the portable jerrycan, which can be worn as part of a body harness and carried by a user in addition to other equipment. Where large amounts of liquid are to be carried or the other equipment is heavy, the weight of the liquid container itself together with the volume it occupies may be a significant factor which reduces the user's freedom of movement. Even when fully emptied of their contents, such conventional containers remain cumbersome if only because of their shape which does not collapse.
In addition to the weight problem, and important part of the container's usefulness is the ability to easily discharge its contents in a resealable fashion. Thus, the design of the container's stopper or cap becomes important. Under field conditions, there is a concern for hygienic use of drinking supplies, and repeated removal of a canteen cap, for example, may allow dirt to enter or to interfere with the proper closing of the screw-on cap. There is also the possibility that the cap may become separated from the container during frequent use. Refilling the container is of overall importance in the design of the container stopper since a maximum opening allows this operation to be completed in the shortest amount of time.
Therefore, it would be desirable to provide a portable container for liquid storage which is lightweight, uses a resealable stopper and is collapsible to conserve volume once emptied.